Grass-like pile product

ABSTRACT

SYNTHETIC GRASS PRODUCTIONS OF IMPROVED QUALITY ARE MADE OF THERMOPLASTIC MONOFILAMENT RIBBONS HAVING A CROSS SECTION IN WHICH THE RIBBONS ARE THICKEST AT THE CENTER, AND TAPER OFF TOWARD BOTH EDGES AND WHICH HAVE A STEM-LIKE PROJECTION ABOUT ITS CENTER ON BOTH SIDES OF THE TAPERED PORTION. THE SYNTHETIC GRASS PRODUCTS ARE PRODUCED BY CONVENTIONAL TUFTING, WEAVING, KNITTING, OR FLOCK-COATING TECHNIQUES AND HAVE RESILIENT SYNTHETIC FOAM ATTACHED TO THE BACKING ON THE SIDE OPPOSITE TO THE EXTENDING RIBBONS.

GRASS'LIKE PILE PRODUCT Filed June-8, 197s Fig.1

-Fig.3 v I Fig.4

3,837,980 GRASS-LIKE PILE PRODUCT Tadashi Nishimura, Kyoto, Yoshifumi Nakayama,

Kusatsu, and Shigeji Yamashita, Kogacho-Ueno, Japan, assignors to Toray Industries, Inc., Tokyo, Japan Filed June 8, 1973, Ser. No. 368,250 Claims priority, appli;at6ig1; zlapan, June 14, 1972,

US. Cl. 16121 28 Claims ABSTRACT OF THE DISCLOSURE Synthetic grass products of improved quality are made of thermoplastic monofilament ribbons having a cross section in which the ribbons are thickest at the center, and taper off toward both edges and which have a stem-like projection about its center on both sides of the tapered portion. The synthetic grass products are produced by conventional tufting, weaving, knitting, or flock-coating techniques and have resilient synthetic foam attached to the backing on the side opposite to the extending ribbons.

BACKGROUND OF THE INVENTION This invention pertains to an improved synthetic grasslike pile product which simulates natural grass. More specifically, this invention relates to a grass-like pile product which may be both indoors and outdoors for a variety of recreational and sports activities.

The prior art reveals that attempts to make grass-like pile products have been made over the past several years. In some instances, the primary objective has been to provide a decorative grass-like product, with no attempt made to provide a product which would withstand permanent outdoor installation and abusive Wear, such as that caused by spiked or cleated shoes.

Other inventions have attempted to provide grass-like pile products for outdoor and indoor sports surfaces and recreational surfaces, but they have had many defects in their appearance and performance.

Since most grass-like pile products have been com prised of cut pile ribbons having a substantially rectangular cross section, they have excess uniformity in their appearance and do not have the deep color and luster of natural turf. In performance, out pile ribbons having a substantially rectangular cross-section are good in their bending properties, but poor in recovery from impact bending. Also, they are easily separated in the direction of the longitudinal axis thereof, when subjected to repeated impacts.

SUMMARY OF THE INVENTION It is an object of this invention to provide a grass-like pile product which simulates the physical characteristics and general appearance of natural turf.

It is another object of this invention to provide a grasslike pile product which has improved resistance to impact and bending.

It is still another object of this invention to provide a grass-like pile product, having pile ribbons which will not separate in the direction of the longitudinal axis thereof, when subjected to repeated impacts.

It is a further object of this invention to provide a grass-like pile product which will not deteriorate either in color or physical characteristics when subjected to abusive treatment in outdoor weather conditions, over extended periods of time.

It is still another object of this invention to provide a grass-like pile product made of pigmented, thermoplastic monofilament piles which have spiral crimps.

3,837,980. Patented Sept. 24, 1974 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross section, greatly enlarged, of the thermoplastic ribbon which is preferred for the present invention.

FIG. 2 shows a cross section, greatly enlarged, of a modified ribbon, wherein the tapered portion is formed by a wave-like side, and which is also preferred for the present invention.

FIG. 3 shows a cross section, greatly enlarged, of a comparative ribbon which is mentioned in the examples.

FIG. 4 shows a cross sectional view of the pile product, showing the construction of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT In order to accomplish the objects of the present invention, a grass-like pile product should be comprised of thermoplastic monofilament ribbons, each having a crosssection in which the ribbon is thickest at its center and tapered off toward both edges, and also having a stem-like projection about the center of each side of the tapered portions, as shown in FIG. 1.

The grass-like pile of this invention normally consists of extended monofilament of to 600 denier, which is extruded from polyamide, polyester, or polyolefin, but preferably polyamides, such as nylon 6, nylon 66, nylon 12 nylon 610 and filament-forming copolymers thereof.

A grass-like pile having a width of between 0.016 to 0.06 inches is preferred for this application, since ribbons having these cross sectional dimensions possess the good appearance and physical properties which promote its usefulness as a substitute for natural turf.

Grass-like products made from cnt pile ribbons having a substantially rectangular cross section have poor recovery from impact bending and such pile ribbons are easily susceptible to permanent deformation. It has become clear from our investigations, that pile ribbons, having a stem-like projection about the center of the cross section, are diflicult to deform permanently by impact bending.

It has also become clear that cut pile ribbons which have a substantially rectangular cross section are first separated in the direction of the longitudinal axis thereof. This separation "accelerates and the pile product wears out under repeated impacts, such as those resulting from usage as a golfing surface. The separations occur most frequently at the center portion of the ribbon having a substantially rectangular cross section, because the impact stress is greatest at the center.

According to the present invention, the grass-like pile ribbon is thickest across its center and tapered olf toward both edges, so that the impact stress is thereby distributed evenly along the cross section of the ribbon. The preferred ribbons have tapered portions forming an angle of between 5 and 30 degrees. The angle of the tapered portion is defined as the angle formed by the intersection of the tangents formed along the edge of the tapered portions.

It is desirable for grass-like pile that the ribbons have a wave-like side along the perimeter of the tapered portion, since the wave-like side serves to deluster the sheen of the flat surface of the ribbon and also to impart a good appearance, like that of natural turf. The cross section of the preferable ribbon has a wave-like side with an interval of from 0.003 to 0.008 inches between adjacent convexities.

' It is known that coloring the grass-like ribbons by adding certain pigments to the thermoplastic materials from which these ribbons are made is preferable, due to the resulting good weather resistance. We have found that a mixture of 0.28 percent phthalocyanine green, 1.64 per cent cadmium yellow, and 0.08 percent carbon black, based on the polymer weight, provides good color depth and sutficient stabilization against ultraviolet light for general applications. These pigments can be supplied by Dainichiseika Color & Chemicals Mfg. Co., Japan.

If desired, the polyamide may be further stabilized by incorporation of any of a number of well known weather stabilizers. The preferable weather stabilizer is Irganox 1222, which is a phenolic antioxidant containing phosphorus, and available from Ciba-Geigy Ltd.

In the present invention, the grass-like pile products are produced by conventional tufting, weaving, knitting, or flock-coating process. Tufting, weaving, and knitting, however, are preferable for producing grass-like pile products which are used for indoor and outdoor sports activities.

In the tufting process, 5 to ply monofilament ribbons are tufted into the backing formed from polyester, acrylic, or polypropylene fibers. Preferably, fabrics, or nonwoven backing formed from polyester fiber, are utilized because of the dimensional stability to moisture change.

A surface pile weight of more than 11 oz./yd. (600 g./m. is required for use in sports activities. The pile height depends on the utilization of the turf. For general play ground activities, such as tennis, volleyball, baseball, and football, a pile height of about A to inch is preferable.

One example of a suitable tufting backing is a fabric woven from polyester filament of 1500 denier, or from polyester spun yarn of 10s/2 and having a weight of about 8.9 oz./yd. (300 g./m.

Another example of a suitable tufting backing is a nonwoven fabric made of a mixture of polyester staples and polypropylene staples, and having a weight of 7.5 oz./yd. (250 g./m.

A typical tufting machine which may be used is the 5/32 gauge cut pile machine manufactured by Courtesy Cobble Bros. Machine Co.

Another preferred method for producing the product of this invention is accomplished by weaving the monofilament pile ribbons and the warp and fill backing yarn together on a conventional Wilton cut-pile loom. A backing composed of yarns fashioned into a fabric having 8 picks per inch and 8 to 14 ounces per square yard is generally satisfactory.

Another preferred method for producing the product of this invention is accomplished by knitting the monofilament ribbons and the backing yarns. The knitting operation may be performed on a conventional fiat-bed, warp-knitting machine, which has been provided with a cutting attachment adapted to cut the loops formed by the ribbon to produce a cut-pile face. An example of the knitting machine is the 200 inch Model F Flatbed Knitting Machine manufactured by Cocker Machine & Foundry.

Still another preferred method for producing the product of the present invention is by a flock-coating process. The monofilament ribbons are cut into short lengths, for example A inch, and deposited on a backing having an adhesive layer thereon, by means of an electrostatic force. For this process, the short fibers should have sufiicient electrical conductivity to be attracted by the electrostatic force. Since thermoplastic monofilaments have excess electrical resistance for this process, they should first be subjected to treatments, which impart a sufficient electrical conductivity. One general method to accomplish this conductivity enhancement is to treat the thermoplastic monofilaments with various types of surface active agents. We have found that a mixture of the composition which appears in Table I, is among the surface active agents perferred for use in such treatments.

TABLE I Compound Parts Potassium lauryl phosphate l5 Stearyl dimethylbetaine 15 Sodium silicate Sodium chloride 4 Typical flock-coating machines are manufactured by H. U. Flock AG, Switzerland.

After weaving, knitting, or tufting, a solution of latex or other adhesive material is applied to the back of the fabric by means of a roller coating process or the like. The latex provides dimensional stability to the fabric and also serves to anchor the ribbons to the backing material. Some examples of suitable latex adhesive solutions are styrene-butadiene rubber, (hereinafter SBR), nitrylbutadiene rubber (hereinafter NBR), and polyethylene/ vinyl acetate copolymer.

It has been found that the durability properties of the turf are further enhanced if a resilient foam backing is applied. A plastic foam, such as polyvinyl chloride. polyethylene or rubber, may be used for purposes of this invention. But polyvinyl chloride closed-cell foam is preferred for outdoor application, because of its more than adequate physical strength and weather resistance. A preferred method of applying the polyvinyl chloride closedcell foam is by coating the back side of the pile product with a plastisol of polyvinyl chloride compounds which contains entrapped air bubbles.

It has also been found from our investigations, that the grass-like pile product comprised of monofilament ribbons having spiral crimps along their surface are more desirable in appearance, as shown in FIG. 4 which illustrates a cross-section of the pile product. The pile 1 formed from pigmented monofilament ribbon has a cross section as shown in FIG. 1 or FIG. 2. The ribbon has a spiral crimp and does not extend in an absolutely straight fashion from backing 2. The ribbon is anchored securely therein by a bonding agent 3, and synthetic foam 4 is applied to the backing to improve the physical properties of the pile product.

One successful method for imparting the spiral crimps to the monofilament ribbons is by twisting several plies of ribbon before making the pile product. Using this method it is more desirable to set the twist by heat treatment. The monofilament ribbons are then made into pile products and each ribbon is separated by brushing.

Another useful method for producing spiral crimps in the monofilament ribbons is to form latent crimps in the ribbons. Conventional methods of producing latent crimps are well known. For example, a typical method is to make unsymmetric heat treatments on the surface of the filament before producing pile products, so that latent crimps will appear upon subsequent heating of the ribbons after weaving, knitting or tufting.

The invention will be more easily understood from the following examples, which are meant to be illustrative, but not restrictive.

Example 1 Monofilament ribbons having a cross section as shown in FIG. 1 were produced from nylon 6 whose relative viscosity is 3.20 at 25 C. in a 98% sulfuric acid solution by a conventional melt extrusion method with a standard screw extruder and auxiliaries. The monofilament ribbons were pigmented by adding a mixture of 1.64 percent cadmium yellow, 0.28 percent phthalocyanine green and 0.08 percent carbon black, based on polymer weight, before spinning. The pigments were mixed with nylon 6 pellets by a Henchel mixer manufactured by Mituimiike Mfg. Co., Japan.

The resultant ribbons were about 300 denier, 0.026 inches wide, and had an angle of the tapered portion of about 10 degrees. Five ply of the ribbons were twisted together by a conventional ring twister and then 2 ply of these twisted ribbons were likewise twisted together. Thus, the number of twists was 5 x 2 turns per inch.

The twisted 10 ply of the ribbon was then tufted into a backing fabric of polyester filaments. The tufting gauge was inch, the stitch was 8 per inch, and the pile height was /2 inch. A SBR latex adhesive, Nipol LX416, which is supplied by Nippon Zeon Co., Ltd., Japan, was applied to the underside of a portion of the backing fabric and dried at 160 C. for 15 minutes.

Two comparative pile products were made in a manner similar to that set forth above, except that the cross section of the pile ribbons differed from the cross section of the pile ribbons of the invention. The comparative pile product A was comprised of monofilament ribbons which had a substantially rectangular cross section and which were about 300 denier and 0.028 inches wide. The comparative pile product B shown in FIG. 3 was comprised of monofilament ribbons which had a cross section similar to that of the invention, except that they had no tapered edges. The monofilament ribbons of comparative pile product B were about 300 denier and 0.027 inches wide.

These three samples of pile products were subjected to a rubbing test to count the number of times they could withstand rubbing before separation occurred in the direction of the longitudinal axis of the ribbons. The testing machine used in the test is described in 118-0823- 1942, as Apparatus for Testing of Color Fastness to Rubbing. A weight of 1.54 lb. (700 g.) was used to accelerate the testing.

Ten specimens from each pile product were tested and the number of times each could be rubbed before the separation began was counted. The results are shown in Table II.

TABLE II Sample Number of times rubbed Invention 13,000 A 8,000 B 7,800

It is clear from the results of this test that the monofilament ribbons of the invention have excellent resistance to separation in the direction of their longitudinal axis.

Example 2 The same three pile products prepared in Example 1 were tested for comparative resistance to impact bendmg.

In this test a Wira Dynamic Loading Machine, manufactured by Daieiseiki Mfg. Co., Japan, was used. The apparatus is well known as an impact bending tester for carpet, and it consists of an impact head which falls a distance of about inches (250 m.) to produce an impact force of about 0.0114 p.s.i. (163 g./crn.

The resistance to impact bending is defined as the difference in the thickness of the pile product before and after 1750 impacts. The thickness of the pile product was measured by Compressive Elasticity Tester, manufactured by Maeda Mfg. Co., Japan, under 0.0014 p.s.i., (20 g./cm. of pressure. The results of this test are shown in Table III.

TABLE III Difference in thick- Sample ness (inches) Invention 0.042 A 0.063 B 0.059

Example 3 A grass-like pile product of this invention was prepared in accordance with Example 1, except that polyethylene/ vinyl acetate copolymer latex was applied to the underside of a portion of the backing fabric. The latex, identified as Evadic, Grade EP50, was supplied by Dainippon Ink & Chemicals Inc., Japan.

A mechanically brothed polyvinyl chloride plastisol foam was then cast upon the back of the pile product. After being fused at 165 C. for 10 min, the closed cell polyvinyl chloride foam had a thickness of 0.23 inches and a density of 35.2 lb./ft. (0.56 g./cm.

The foam compound used here was prepared in accord ance with the proportions shown in Table IV and an Oakes Continuous Mixer was used to disperse gas into the polyvinyl chloride plastisol.

Blending-grade resin also supplied by the Japanese Geon (10., Ltd, Japan.

3 Silicone compound surfactant, supplied by Toray Silicone Co., Ltd., Japan.

The resultant pile product possessed excellent wear properties when used as a golf surface.

Example 4 A grass-like product of this invention was prepared in accordance with the procedure in Example 1, using 10 ply 300 denier polyester monofilament ribbon having a cross section as shown FIG. 1.

The resultant pile product having a pile height of /2 inch had a stiffer hand than the product of Example 1. This product made an excellent covering for floors in a golf-course club house.

Example 5 A grass-like product of this invention was prepared according to the procedure of [Example 1, using 15 ply of 200 denier polypropylene monofilament ribbon having a cross section as shown FIG. 1. The polypropylene polymer, identified as Noblen, Grade 131-1-4, was supplied by Mitui Toatu Chemicals Inc. A closed-cell polyethylene foam, having a thickness of inch and a density of 6 lb./ft. (0.095 g./cm. was then adhered to the resultant pile product which had a pile height of inch.

This pile product was used as a covering for an indoor tennis court and had a good ball-rebound property and good wear resistance.

Example 6 8 ply of 500 denier pigmented nylon 6 monofilarnent ribbon, having a cross section as shown FIG. 2, was woven with a polyester warp and fill backing on 21 Wilton cut pile loom to produce a grass-like pile product. Each ribbon had ten convexities along both sides of the tapered portions of the cross section.

The pile product had 35 oz./yd. (1200 g./m. of nylon surface pile with a pile height of /2 inch. The polyester base was woven frorn 10s/6 spun polyester yarns, using 8 picks per inch, to yield a fabric of 25 oz./yd. (850 g./m. SBR latex was applied to the pile product in accordance with the procedure of Example 1. The resultant product possessed the deep color and luster of natural turf and excellent wear properties, when subjected to heavy foot traffic.

The reflectance of light from the face of the microfilament ribbon, having a cross section as shown in FIG. 2, was measured. The results of these measurements are shown in Table IV. The measurements were made using a Micro-luster Meter, manufactured by Ionan Mfg. Co., Japan. The method of this measurement was in accordance with the procedure reported in the Journal of the Textile Machinery Society of Japan, Vol. 24, pg. 756 (1971), and Dyeing Industry, Vol. 18, pg. 696 (1970).

TABLE V Reflectance 1 Sample (percent) Invention (Example 6) 20 Comparative Ribbon X 47 Comparative Ribbon Y 58 Natural Turf (grass) -23 Percent reflectance in reference to a white plate made from magnesium oxide.

A monofilament ribbon of 500 denier, having the cross section shown in FIG. 1.

A monofilament ribbon of 500 denier, having a substantially rectangular cross section.

Example 7 A grass-like product was produced by a flock-coating process, using 200 denier pigmented nylon 6 monofilament ribbons, each having a cross section as shown FIG. 1. Nylon monofilament fiber was cut into inch long pieces. The cut fibers were then immersed in a mixture of surface active agents, as mentioned above, and excess agents were removed from the cut fiber by a centrifuge machine. Then the cut fibers were placed in a room having a relative humidity of 40%, for 24 hours. Thereafter, the resultant cut fiber exhibited an increase in moisture content from between 6% to 8%, based on the weight of fiber.

The cut fiber was then deposited on the backing fabric, having an adhesive layer of an acrylic compound, by conventional methods. Then, the pile product was dried at 140 C. for 15 minutes.

The resultant pile product had a pile density of 5.9 oz./yd. (200 g./m. and was considered satisfactory for light service applications.

Example 8 A grass-like product of this invention was prepared in accordance with the procedure of Example 1, except that the nylon 6 monofilament ribbon of 300 denier was heated with a hot plate to a temperature of 140 C. on its surface, before being twisted. Ten ply of this twisted nylon 6 monofilament was tufted into a backing fabric of polyester filament, similar to that used in Example 1.

After application of SBR latex, the resultant pile product was exposed to 140 C. superheated steam for period of one minute. After this steaming process, the monofilament pile ribbon hadspiral twists and the resultant pile product possessed a softer hand than the product of Example 1 and excellent appearance.

Although this invention has been described with reference to specific forms of synthetic grass products, and although these have been described in specific terms in the specification and in the abstract of the disclosure, having reference to the particular forms shown in the drawings, it will be appreciated that a wide variety of variations may be made without departing from the spirit and scope of the invention. For example, certain features of the invention may be used independently of other features, variations may be made with respect to the relative sizes and proportions of the various elements of the blades of synthetic grass or their arrangement with respect to their base, and equivalent means of formation may be substituted for those specifically described, without departing from the spirit and scope of the invention as defined in the appended claims.

What we claim is:

1. A synthetic grass product consisting of a backing material to which is attached and from which extends a grass blade-like product comprising a ribbon of synthetic thermoplastic monofilament material which, in cross section, is thickest at its center and tapers off toward spaced-apart edges, said center includes a stem-like projection which extends lengthwise along the ribbon and which projects outward from both sides of the blade surface, said edges having a thickness which is substantially less than the thickness of said stem-like projection.

2. The product of Claim 1 wherein said thermoplastic monofilament material is selected from the group consisting of polyamide, polyester, and polyolefin.

3. The product of Claim -1 wherein said thermoplastic monofilament material is selected from the group consisting of pigmented polyamide, pigmented polyester, and pigmented polyolefin.

4. The product of Claim 1 further characterized by resilient synthetic foam adhered to said backing material on the side opposite that from which said ribbons extend.

5. The product of Claim 4 wherein said resilient synthetic foam is selected from the group consisting of polyvinyl chloride, polyethylene, polypropylene, and rubber.

6. The product of Claim 1 wherein said ribbons are tufted into said backing material.

7. The product of Claim 1 wherein said ribbons are woven into a warp and fill backing material.

8. The product of Claim 1 wherein said ribbons are knitted with the fibers of said backing material.

9. The prodlct of Claim 1 wherein said ribbons are deposited on said backing material by means of flockcoating.

10. The product of Claim 1 wherein said ribbons have from to 600 denier per ribbon.

11. The product of Claim 1 wherein said ribbons have a width of from 0.016 to 0.06 inches.

12. The product of Claim 1 wherein the ribbons have an angle of the tapered portion of from 5 to 30 degrees.

13. The product of Claim 1 wherein said ribbons have a cross section wherein the tapered portions have wavelike sides.

14. The product of Claim 13 wherein said wave-like sides of said cross section have an interval of from 0.003 to 0.008 inches between adjacent convexities.

15. The product of Claim 1 wherein said ribbons extending from said backing material have spiral crimps.

16. The product of Claim 15 wherein said spiral crimps have a twisted configuration.

17. The product of Claim 15 wherein said spiral crimps are latent crimps characterized by unrelieved stresses in the molecular structure of said ribbon.

18. A blade of synthetic grass which comprises a rib bon of synthetic thermoplastic monofilament material which, in cross section. is thickest at its center and tapers off toward spaced-apart edges, said center including a stem-like projection which extends lengthwise along the ribbon and which projects outward from both sides of the blade surface, said edges having a thickness which is substantially less than the thickness of said stem-like projection.

19. The product of Claim 18 wherein said thermoplastic material is selected from the group consisting of polyamide, polyester, and polyolefin.

'20. The product of Claim 18 wherein said thermoplastic is selected from the group consisting of pigmented poly-amide, pigmented polyester, and pigmented polyolefin.

21. The product of Claim 18 wherein said ribbon has from 100 to 600 denier per ribbon.

22. The product of Claim 18 wherein said ribbon has a width of from 0.016 to 0.06 inches.

23. The product of Claim 18 wherein the ribbon has an angle of the tapered portion of from 5 to 30 degrees.

24. The product of Claim 18 wherein said ribbon has a cross section wherein the tapered portions have Wavelike sides.

25. The product of Claim 24 wherein said wave-like sides of said cross section have an interval of from 0.003 to 0.008 inches between adjacent convexities.

26. The product of Claim 18 wherein said ribbon has spiral crimps.

27. The product of Claim 26 wherein said spiral crimps have a twisted configuration.

9 10 28. The product of Claim 26 wherein said spiral crimps 3,332,828 7/ 1967 Fari'a 161--177 are latent crimps characterized by unrelieved stresses in 3,565,742 2/1971 Stephens et a1. 161-21 UX the molecular structure of said ribbon. 3,740,303 6/ 1973 Alderson et a1. 161-21 References Cited 5 WILLIAM E. SCHULZ, Primary Examiner UNITED STATES PATENTS US. Cl. X.R. 3,135,646 6/1964 Hayden 161-177 E 151 2, 177 

